<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <script type="text/javascript" src="./jquery-1.11.0.js"></script>
</head>
<body>
<span>
    通过模拟mouseEvent的mouseDown事件，可以触发select的下拉出现的效果
</span>

<select id="ts">
    <option value="1">1</option>
    <option value="2">Lorem ipsum dolor s.</option>
    <option value="3">3</option>
</select>

<input type="button" id="click" value="Click"/>


<script type="text/javascript">
    $(document).ready(function() {
        $('#click').click(function() {
            open($('#ts'));
        });
    });

    function open(elem) {
        if (document.createEvent) {
            var e = document.createEvent("MouseEvents");
            e.initMouseEvent("mousedown", true, true, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
            elem[0].dispatchEvent(e);
        } else if (element.fireEvent) {
            elem[0].fireEvent("onmousedown");
        }
    }
</script>
</body>
</html>